This invention relates to the manufacture of storage batteries, and in particular relates to washing and drying the completed batteries prior to shipment in order to remove acid and dirt deposited on the battery surface.
Manufacturing storage batteries causes the battery surfaces to collect various contaminants. The primary contaminant is battery acid, which is deposited on the battery surface by gassing and bubbling of the electrolyte during battery charging. Lead dust, grease, and other types of dirt are also deposited on the battery surface during manufacture. Hence, it is common industry practice to wash the batteries before shipping to remove the contaminants and give the battery a clean appearance.
Prior art battery washers typically involve a conveyor system with water spray nozzles and brushes, followed by an evaporative dryer. Soap is usually added to the water to lift the insoluble dirt from the battery surface. The soap usually contains a highly alkaline material to neutralize acid from the battery, but the soap is then made less effective by the salts resulting from the neutralization process.
While the prior art wash systems are effective in cleaning batteries, they consume large amounts of water and soap, which becomes contaminated waste water requiring treatment before disposal or reuse. They also require a significant expenditure of heat energy, and do not reclaim any of the electrolyte acid.
A somewhat analogous situation existed in the practice of washing dry-charge battery plates, which I addressed in my U.S. Pat. No. 4,572,746. That patented process remedied the waste of formation acid, and the by-products of large volumes of contaminated waste water and hazardous solid waste sludge, which existed in the prior art processes which proceeded it. Persons interested in the full particulars of that process are urged to read the patent in its entirety, but in general terms, it includes washing the formed plates first in a slow-flow tank to remove the majority of acid, and then re-washing the plates in a fast-flow rinse tank to remove the residual acid. The wash water in the slow-flow tank effectively removes the acid from the plates. The resulting highly acidic solution is pumped from the wash tank to a holding tank for use, such as making new electrolyte for wet battery production or making re-package acid. Conversely, the relatively low acidity in the fast-flow tank allows that water to be purified in an ion exchange bed and recycled in the wash system. Thus, most of the acid is reclaimed for further use, while the amount of contaminated water and solid waste sludge is greatly reduced.
An objective in the present invention is to achieve similar economy in the process of washing completed batteries. That is, I seek to reclaim and then reuse the electrolyte acid to the extent practical, to filter and regenerate the wash water for continuous reuse in the wash system, and to dry the batteries with a reduced expenditure of energy. These objectives, and the manner in which they are achieved, will be more fully understood in the description which follows.
As a generalized example, the particular embodiment of the invention described herein is estimated to reduce water and soap consumption by 100 fold, and reduce combined electrical and heat consumption by 10 fold, over comparable prior art washing systems. It will reclaim over 99% of the electrolyte acid, in only 40 gallons of wash water per 4,000 batteries, while maintaining an output of 10 batteries/min. This 40 gallons of wash water contains the reclaimed electrolyte in an approximately 5% acid concentration, and is recycled as an acid solution which can be used to make new electrolyte. The apparatus operates at wash water temperatures of 80.degree.-100.degree. F., and dries the batteries with room temperature air only.
It should be noted that although the described apparatus and method is directed to washing storage batteries, the same principles and similar methods can be used for other articles in which washing is used to remove both non-soluble dirt and water soluble acids or salts, such as with semiconductor chips, "pickled" steel, and like articles. However, some variations would likely have to be made in the carrier, rinse station configuration and number, brushes and other components necessary to accommodate the different size, shape and acid content of such articles.